Electric discharge tube



1935- E. oosi'ERl-luls ELECTRIC DISCHARGE TUBE Filed Feb. 21. 1930 INVENTOR ATTORNEY on four supporting rods 5 and is covered at the Patented Aug. 13, 1935 ELECTRIC DISCHARGE TUBE Ekko Ousterhuis, Eindhoven, Netherlands, assignor, toRadio Corporation of America, a corporation of .Delaware Application February 21, 1930, Serial No. 430,152 In Germany April 15, 1929 2 Claims.

The invention relates to an electric discharge tube. comprising an anode which consists of two plate-shaped members arranged on either side of the grid and connected to each other'by means,

of a fork or strap reaching over the grid. Heretofore the rigidity of this anode construction has proved to be unsatisfactory as the anode is slight ly movable in a lateral direction, so that undesirable alterations of the position of the anode may occur, for example when the discharge tube is exposed to shocks. Alterations of;thefcharacteristic magnitudes of the discharge tube or even short-circuits between the anode and grid may result therefrom.

The invention has for itsobject to obviate these disadvantages.

According to the invention, the strap or fork which connects the twoplatesconstituting the anode and which extends over the grid is mechanically connected to the latter by means of one or more members having an insulating part.

The term grid is to be understood to mean the whole grid construction, including'the grid supports and the members whereby, if desired, the grid is covered. r

The invention will be more clearly understood by referring to the accompanying drawing which represents, by way of example, one particular embodiment of the invention and in which Figure 1 is a perspective view of a tube; Figure 2 is a longitudinal section, and Figure 3 is a cross section along the line I1'I-III of Figure 2, which is a section along the line IIII of Figure 3.

Referring to the drawing, the discharge tube I has a stem 2 to which are secured various electrodes. On the stem is mounted, inter alia, an incandescent cathode surrounded by a control grid, these two being however not visible in Figure 1 of the drawing. The control grid is surrounded by a screen grid 3 which constitutes an electrostatic screen between the control grid and the anode of the discharge tube. This anode consists of two plate-shaped members 4 which are arranged on either side of the screen grid 3 and of which only one is visible in Figure 1 of the drawing. The grid 3 has a wire which is wound top by a metallic plate 6. The support rods 5 are secured to a plate-shaped disc "I provided with a rim 8 which is located at a short distance from the wallof the discharge tube. By means of support wires, not shown in Figure 1 of the drawing, the disc I is secured to the stem of the discharge tube. The plates 4 are-anchored to the disc I by means of supporting wires 9 and l0 limbed fork bestriding the upper closed end of said which are connected to each other by means of the insulating part II constituted, for example,

by a glass bead. The two plates 4 are connected to each other by a fork or strip l2'which reaches over the electr c-static screen 3, said strip being 5 connected to a wire l3 which at the top of the discharge tube is led out of the latter and which is connected to the terminal l4 provided on the bulb of the discharge tube. The current supply conductors of'the other electrodes are taken out 1 through the stem 2 and are connected to contact pins I5 on the base I 6.

In order to increase the rigidity of the anode construction and to inhibit the anode from lateral motions and to thus prevent alterations of the 15 characteristic magnitudes of the discharge tube, the fork or strap I2 is insulatedly connected to one of the supporting rods 5 of the electro-static screen 3. As appears from the drawing, this connection is established by a spacer comprising 20 support wires I1 and [8 which are mechanically secured to but electrically insulated from each other by means of an insulating member [9 sealed to the wires, such as a glass bead. It is evident that the strap I2 may also be connected 25 to other parts of the grid, for example, to the plate 6.

In triodes, it is apparent that the anode may be connected to the control grid, just as in the present construction the anode is connected to the screen grid 3.

As best shown in Figures 2 and 3, a looped filament cathode 20 is mounted on the stem 2 and is surrounded by a control grid 2| having side rods or supports 23in the press of the stem. The 35 control grid is surrounded by the screen grid 3 which has at its lower end the transverse shield 8 which is carried on the stem by supports 23, and extends transversely of the tube between the stem and the anode plates 4. The cathode 40 is supported in the usual way by means of a hook on the end of a cathode support 24.

I claim:

1. An electrical discharge device comprising a sealed envelope having a reentrant stem, a boxlike grid electrode coaxially mounted on said stem and having its upper end closed, an anode lead sealed into the tip of said envelope in alignment with said stem and having on its inner end a twogrid electrode, an anode comprising a pair of plates one on each of the limbs of said fork and on opposite sides of said grid electrode, and two insulating braces, one parallel to and the other transverse of the longitudinal'axis of said stem,

the first brace secured to said plate and one end of said grid electrode and the second brace secured to a limb of said fork and to said grid electrode near the other end thereof.

2. An electrical discharge device comprising a sealed envelope having a reentrant stem and enclosing a screen grid electrode mounted on the inner end of said stem, an anode lead sealed into the tipof said envelope opposite and in alignment with said stem with its inner end in the form of a fork bestriding the adjacent end of said grid electrode with its two limbs on opposite sides of said grid electrode, an anode comprising two plates secured to the limbs of said fork, a transverse metal shield on the end of said screen grid electrode adjacent said stem and interposed between said stem and. said anode plates, insulating braces perpendicular to said shield and secured to each of said plates and to said shield, and an insulating brace parallel to said shield and secured to a limb of said fork and to said grid electrode.

EKKO OOSTERHUIS. 

